In order to investigate the effect of low-angle grain boundary(LAGB) on the high-temperature creep behavior of a second-generation nickel-based single-crystal(SX) superalloy, the high-temperature creep fracture and interrupted experiments are carried out at 1100 ℃/137 MPa using plate-shaped samples with different grain boundary misorientations. The results show that after standard heat treatment, fine MC carbides are formed at the LAGB with the misorientation of 7° in alloy GB-7, while blocky M6C carbides are formed at the LAGB with the misorientation of 12° in alloy GB-12. The high temperature creep life of the investigated alloys decreases with increasing the misorientation degree. The creep life of alloy GB-12 is only 40% of that of the single crystal alloy. Further investigation reveals that LAGB migration occurrs in both the GB-7 and GB-12 alloys during high-temperature creep, but the migration distance of the GB-12 alloy is lower than that of the GB-7 alloy. Blocky M6C carbides in alloy GB-12 hinder the grain boundary migration, leading to strain concentrations at the LAGB region. Cracks tend to initiate at the low-angle grain boundary either inside GB-12 alloy or on its surface, leading to a significant reduction in its creep life. This study can provide guidance and data support for improving the tolerance of LAGBs in high-temperature creep.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |